Conventionally, a fastening means for attachably and detachably coupling a plurality of members or parts to one another includes mainly a fastening metal-fitting such as a bolt having a screw, or a pin or cotter utilizing a wedge action, elasticity, or friction.
Also, a fastening means other than one employing the above-described fastening metal-fitting includes, for example, as described in Japanese Patent Laid-Open Publication No. 8-128420, a structure in which: a T-slot is formed in each of connection surfaces of two members to be fastened; a linking member, in which a pair of protrusions and a pair of elastic protrusions are symmetrically formed on a center wall regarded as a center, is used; the protrusion and the elastic protrusion on each side are inserted into the respective T-slots in a direction almost orthogonal to a connection surface and are engaged inside; and the two members are engaged inside and fastened.
One utilization example of the fastening assembly assembled by the above-described fastening means includes a fluid pressure cylinder unit constituting a cylinder tube fastened to an attachment. This fluid pressure cylinder unit can increase a driving force or stroke as an actuator by fastening and assembling a plurality of fluid pressure cylinders to one another, or improve rigidity and actuation accuracy of the entirety by fastening an attachment, such as a guide unit provided with a guide rod for supporting a piston rod, to a fluid pressure cylinder.
In many cases, the cylinder tube serving as a body of the fluid pressure cylinder and an attachment body are members having comparatively large weight and are mutually subjected to reaction forces of the rod during actuation. Therefore, the cylinder tube and the attachment in the fluid pressure cylinder must be certainly fastened, so that such a fastening means includes utilizing a structure in which interior engagement is carried out mutually via the above-described fastening metal-fitting such as a bolt or the above-described linking member.
However, in a fastening structure using the fastening metal-fitting such as a bolt, a large-volume bracket must be interposed on a surface of a constituent member to be fastened. Or, in the case of using the bolt, its head protrudes from a member surface. These are large factors for hindering a space from being saved since the space for installing each member is limited depending on recent device downsizing.
Meanwhile, in a fastening structure in which the interior engagement is carried out via the linking member, since there is nothing protruding from a surface of the member such as the head of the bolt even in a fastened state, this structure is suitable for saving the installation space. Further, mutual relative arrangements or fastening locations of two members can be arbitrarily set and changed since providing a screw hole or pin hole is not required. However, even if each of the protrusion and the elastic protrusion on each side is inserted into the T-shaped groove in a direction almost orthogonal to their connection surface, they can be easily separated by being detached in an opposite direction and therefore it is difficult to fasten them firmly.
An object of the present invention is to provide a fastening assembly and a fastener which are suitable for saving the installation space, capable of arbitrarily and easily setting the mutual relative arrangements and fastening positions of the respective members, and capable of firmly fastening them.
Another object of the present invention is to provide a fluid pressure cylinder unit having various structures in each of which there is nothing protruding from the surfaces while cylinder tubes are firmly fastened to each other.
Another object of the present invention is to provide a fluid pressure cylinder unit in which an arbitrary fluid pressure cylinder is combined with an arbitrary attachment so as to be fastened easily and firmly.